/*
*
*    This program is free software; you can redistribute it and/or modify it
*    under the terms of the GNU General Public License as published by the
*    Free Software Foundation; either version 2 of the License, or (at
*    your option) any later version.
*
*    This program is distributed in the hope that it will be useful, but
*    WITHOUT ANY WARRANTY; without even the implied warranty of
*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
*    General Public License for more details.
*
*    You should have received a copy of the GNU General Public License
*    along with this program; if not, write to the Free Software Foundation,
*    Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*
*    In addition, as a special exception, the author gives permission to
*    link the code of this program with the Half-Life Game Engine ("HL
*    Engine") and Modified Game Libraries ("MODs") developed by Valve,
*    L.L.C ("Valve").  You must obey the GNU General Public License in all
*    respects for all of the code used other than the HL Engine and MODs
*    from Valve.  If you modify this file, you may extend this exception
*    to your version of the file, but you are not obligated to do so.  If
*    you do not wish to do so, delete this exception statement from your
*    version.
*
*/

#include "precompiled.h"

static const uint32 pulCRCTable[256] =
{
	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
	0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
	0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
	0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
	0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
	0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
	0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
	0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
	0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
	0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
	0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
	0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
	0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
	0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
	0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
	0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
	0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
	0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
	0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
	0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
	0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
	0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
	0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
	0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
	0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
	0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
	0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
	0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
	0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
	0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
	0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
	0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
	0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

void EXT_FUNC CRC32_Init(CRC32_t *pulCRC)
{
	*pulCRC = -1;
}

CRC32_t EXT_FUNC CRC32_Final(CRC32_t pulCRC)
{
	return ~pulCRC;
}

void EXT_FUNC CRC32_ProcessByte(CRC32_t *pulCRC, unsigned char ch)
{
	CRC32_t ulCrc = *pulCRC;
	ulCrc = pulCRCTable[(ulCrc & 0xFF) ^ ch] ^ ((ulCrc ^ ch) >> 8);
	*pulCRC = ulCrc;
}

void EXT_FUNC CRC32_ProcessBuffer(CRC32_t *pulCRC, void *pBuffer, int nBuffer)
{
	CRC32_t ulCrc = *pulCRC;
	uint8* pb = (uint8*)pBuffer;

	for (int i = 0; i < nBuffer; i++)
	{
		ulCrc = pulCRCTable[(ulCrc & 0xFF) ^ pb[i]] ^ (ulCrc >> 8);
	}

	*pulCRC = ulCrc;
}

byte COM_BlockSequenceCRCByte(byte *base, int length, int sequence)
{
	byte *p;
	char chkb[64];
	CRC32_t crc;

	if (sequence < 0)
		Sys_Error("%s: sequence < 0\n", __func__);
	p = (byte *)pulCRCTable + sequence % 0x3FC;
	if (length > 60)
		length = 60;

	Q_memcpy(chkb, base, length);

	chkb[length] = p[0];
	chkb[length + 1] = p[1];
	chkb[length + 2] = p[2];
	chkb[length + 3] = p[3];

	CRC32_Init(&crc);
	CRC32_ProcessBuffer(&crc, chkb, length + 4);
	return CRC32_Final(crc);
}

NOXREF BOOL CRC_File(CRC32_t *crcvalue, char *pszFileName)
{
	NOXREFCHECK;
	FileHandle_t fp;
	byte chunk[1024];
	int nBytesRead;
	int nSize;

	fp = FS_Open(pszFileName, "rb");

	if (!fp)
		return 0;

	nSize = FS_Size(fp);
	if (nSize == -1)
		return 0;

	while (nSize > 0)
	{
		if (nSize > 1024)
			nBytesRead = FS_Read(chunk, 1024, 1, fp);
		else
			nBytesRead = FS_Read(chunk, nSize, 1, fp);

		if (nBytesRead > 0)
		{
			nSize -= nBytesRead;
			CRC32_ProcessBuffer(crcvalue, chunk, nBytesRead);
		}

		if (FS_EndOfFile(fp))
			break;

		if (!FS_IsOk(fp))
		{
			FS_Close(fp);
			return 0;
		}
	}
	FS_Close(fp);
	return 1;
}

int CRC_MapFile(CRC32_t *crcvalue, char *pszFileName)
{
	FileHandle_t fp;
	byte chunk[1024];
	int i;
	int l;
	int nBytesRead;
	dheader_t header;
	int nSize;
	lump_t *curLump;
	int32 startOfs;
	int nLumpID;

	nLumpID = 0;
	if (Q_stricmp(com_gamedir, "bshift") == 0)
		nLumpID = 1;

	fp = FS_Open(pszFileName, "rb");

	if (!fp)
		return 0;

	nSize = FS_Size(fp);
	if (nSize == -1)
		return 0;

	startOfs = FS_Tell(fp);
	if (FS_Read(&header, sizeof(dheader_t), 1, fp) != sizeof(dheader_t))
	{
		Con_Printf("Could not read BSP header for map [%s].\n", pszFileName);
		FS_Close(fp);
		return 0;
	}
	i = LittleLong(header.version);
	if (i != HLBSP_VERSION)
	{
		Con_Printf("Map [%s] has incorrect BSP version (%i should be %i).\n", pszFileName, i, HLBSP_VERSION);
		FS_Close(fp);
		return 0;
	}
	for (l = 0; l < HEADER_LUMPS; l++)
	{
		if (l == nLumpID)
			continue;

		curLump = &(header.lumps[l]);
		nSize = curLump->filelen;
		FS_Seek(fp, startOfs + curLump->fileofs, FILESYSTEM_SEEK_HEAD);

		while(nSize > 0)
		{
			if (nSize > 1024)
				nBytesRead = FS_Read(chunk, 1024, 1, fp);
			else
				nBytesRead = FS_Read(chunk, nSize, 1, fp);

			if (nBytesRead > 0)
			{
				nSize -= nBytesRead;
				CRC32_ProcessBuffer(crcvalue, chunk, nBytesRead);
			}
			if (!FS_IsOk(fp))
			{
				FS_Close(fp);
				return 0;
			}
		}
	}
	FS_Close(fp);
	return 1;
}
